Is it true though that a drug such as Deca Durabolin (nandrolone decanoate) is less likely to cause hair loss than testosterone?
A: Yes. This may be because nandrolone is converted to DHN rather than DHT. Dihydronandrolone is almost the same molecule as DHT Dihydrotestosterone Androstanolone, but without the 19-methyl group. While DHT binds to the androgen receptor (AR) more strongly than testosterone does, DHN binds fairly weakly to the AR, less so than nandrolone itself does.
Nandrolone itself is a 5a -reductase inhibitor (although it yields DHN in the process). So less DHT is produced if nandrolone is present. Nandrolone will also inhibit natural production of testosterone, so there is less testosterone available to be converted to DHT.
The testosterone user has high levels of DHT in the scalp, and therefore a lot of androgen in the scalp. The nandrolone user has low levels of DHT, instead having DHN, which is less potent.
Furthermore, DHT probably has hair loss activities not mediated by the androgen receptor, but by other proteins in the scalp and via the immune system. DHN may not have these activities.
More importantly, what is observed is that nandrolone is quite good for keeping one’s hair, whereas testosterone is not, for those genetically predestined to lose their hair.
The price one pays for this, though, is that nandrolone is not as effective an anabolic as testosterone.